Unit 3: Fingerprints (part 3)

A. Properties that make a fingerprint useful for identification =

 1. its unique, characteristic ridges

 2.its consistency over a person’s lifetime,

 3. the systematic classification used for fingerprints (Henry Number)

III. Fingerprints as Evidence

B. No legal requirements in US on # of points/ minutiae that must match before certain it belongs to individual

--criminal courts generally accept 12 points

C. Computer-Based fingerprint files 

1. AFIS = Automated Fingerprint Identification System

 a. started in the 60s

 b. by 80s at least 5 systems in use

 c. problem????

 d. recently IAFIS available (Integrated)

AFIS) . . . includes FBI criminal database of known

fingerprint cards

2. Other electronic databases for law enforcement

a. CODIS = Combined DNA Indexing System

 b. IBIS = Integrated Ballistics Identification System

C. Computer-Based fingerprint files (cont.)

DNA Fingerprint Ballistics Data

3. Each electronic database has . . .  

a. “knowns” file

 b. “forensic” file = images or profiles from unsolved cases

C. Computer-Based fingerprint files (cont.)

AND

1. Patent = clearly recognizable Ex. Made with grease,

dirt, oil, blood, etc.

  2. Plastic = recognizable indentation in a soft receiving surface such as butter, silly putty, or tar

 3. Latent = not visible, requires further processing for comparison

D. Types of Evidentiary Fingerprints

Latent prints are impressions left by friction ridge skin on a surface, such as a tool handle, glass, door, etc.

Prints may be collected by revealing them with a dusting of black powder and then lifted with a piece of clear tape.

Did you know? Camel hair is the most common animal hair used to make fingerprint brushes. Now many brushes (like the one above) are made out of fiberglass.

Fingerprint Processing Videos

http://www.youtube.com/watch?v=w7wUuRiMCuM&feature=relmfu

http://investigation.discovery.com/videos/almost-got-away/